Excruciatingly bad.
'Tarzan & Jane' is a rather terrible excuse for a sequel, as it shoehorns in three separate stories which have nothing to do with the first film and add absolutely zero to it. Awful new characters, average animation, disappointing new cast and nowhere near noteworthy music. They made it poorer in every way.
I can now understand why they titled the third film as 'Tarzan II', probably trying to airbrush this from existence. I'm struggling to find a positive about this film, perhaps the two seconds of Phil Collins' original music at the very beginning? Of the three stories, I guess the final one is best? I'm scraping the barrel.